Osmolality Changes during Hemodialysis

Abstract

We studied the influence of both a high-glucose-concentration dialysate (717 mg/dl) and intravenous mannitol (1g/kg) on the serum osmolality changes in stable patients on chronic dialysis. During regular dialysis, serum osmolality fell 10 mosmol/kg H₂O. This fall was reduced to 5.2 mosmol/kg H₂O when the high-glucose-concentration dialysate was used, and to 4.3 mosmol/kg H₂O when intravenous mannitol was used. When the two methods were combined, the serum osmolality fall was reduced to 1.7 mosmol/kg H₂O. The clinical signs of disequilibrium declined (from 67% to 10%) in parallel with the decline in serum osmolality changes. This fall was independent of the ultrafiltration rate. A high-glucoseconcentration dialysate and intravenous mannitol can each reduce the osmolality changes that occur during hemodialysis, but when used alone, intravenous mannitol is more effective of the two. The reduction of osmolality changes also leads to reduction of the mild clinical signs usually associated with disequilibrium.